Method of plating beryllium article with zinc

ABSTRACT

Beryllium article is chemically plated with metallic zinc with a high fixedness and uniformity by treating same with an aqueous acid solution containing zinc cation (Zn ) and fluorine anion (F ) and having a zinc content of 0.35 to 14 percent by weight.

United States Patent Kawada et al.

[451 Aug. 28, 1973 METHOD OF PLATING BERY LLIUM ARTICLE WITH ZINC Junichiro Kawada, Tokyo; Nobuo Sato, Kawasaki, both of Japan Assignee: Fujitsu Limited, Kawasaki-shi, Japan Filed: July 2, 1971 Appl. No.: 159,408

Inventors:

Foreign Application Priority Data [56] References Cited UNlTED STATES PATENTS 2,901,408 8/1959 Townsend 204/38 B 2,580,773 l/l952 Heiman .1 117/130 R 2,873,216 2/1959 Schnable... 117/130 R 2,676,916 4/1954 Zelley .1 204/38 B X Primary ExaminerRalph S. Kendall Attorney-Robert E. Burns et a1.

[ ABSTRACT Beryllium article is chemically plated with metallic zinc with a high fixedness and uniformity by treating same with an aqueous acid solution containing zinc cation (Zn**) and fluorine anion (F') and having a zinc content of 0.35 to 14 percent by weight.

11 Claims, 1 Drawing Figure 2 Qzn 0 1 I l l l 1 PLATING TIME (second) METHOD OF PLATING BERYLLIUM ARTICLE WITH ZINC The present invention relates to a method of plating a beryllium article with zinc, more particularly, relates to a method of chemically plating a beryllium article with zinc with a high fixedness and uniformity.

Recently, in the electronics and other industrial fields, it is desirable to make the weight and size of the apparatus used in these fields lighter and smaller. The smaller and lighter apparatus in industrial uses are very valuable for decreasing necessary energy for driving the apparatus, generation of undesirable frictional heat and wear loss during driving the apparatus, and necessary area and space for setting the apparatus, and for advancing driving velocity and processing or handling properties, for example, transportation.

Particularly, it is very important economically in the fields of space communication satellites and space ships to make the materials lighter and smaller in order to save the propulsive load of a rocket for launching the spacecrafts.

Now and in the past, the apparatus desired to be made lighter and smaller are generally manufactured by using aluminium or aluminium alloys such as Al-Cu, Al-Cu-Si, Al-Si, Al-Cu-Mg, Al-Mg, Al-Mn, Al-Cu-Ni and Al-Zn-Mg. However, it is desired in certain fields, such as the space industry that the material for the apparatus be lighter than aluminium and the aluminium alloys.

Recently, utilization of beryllium having a low specific gravity of 1.84 instead of the aluminium having a specific gravity of 2.70 has been attempted in order to accomplish the above desire. Unfortunately, the beryllium has a high chemical activity which causes variable difficulties in the actual uses. Accordingly, it is necessary that the surface of the beryllium article be plated with a suitable metal such as zinc for protecting the surface from undesirable chemical reactions such as oxidation or handling properties, for example, in transportation.

However, it is very difficult to plate the beryllium article with other metals such as zinc, copper, silver, gold, nickel, chromium and the like with a high fixedness or adherence owing to the high chemical activity of the beryllium.

It is well-known that the aluminium and its alloys can be plated with zinc by the conventional zinc-plating method wherein an alkaline aqueous solution of a zincate is utilized as a plating liquid. However, the conventional zinc-plating method for aluminium is unsuitable for beryllium. Generally, the plating of the conventional material with copper, silver, gold, nickel, chromium or the like is effected by, for example, electro plating, hot galvanizing, vacuum plating or metallic cementing methods. The beryllium article can not be sufficiently plated with the above metals by any of the above-mentioned conventional methods owing to the high chemical activity thereof. Therefore, it is advantageous that the surface of the beryllium article be previously covered with a suitable metal such as zinc having a high fixedness for the above metals.

An object of the present invention is to provide a method of plating a beryllium article with zinc with a high fixedness and uniformity.

Another object of the present invention is to provide a method for forming a zinc plating layer on a beryllium article, which zinc plating layer is very valuable for further plating said beryllium article with copper, silver, gold, nickel, chromium and the like through the zinc layer.

These and further objects will become more apparent upon reading the detailed description set forth hereinbelow and the accompanying drawing which is a graph showing relationships of plating time for a beryllium article with respect to precipitation quantity (Q of zinc and dissolution quantity (Q of beryllium.

In accordance with the method of the present invention, the beryllium article, which is preferably cleaned by a proper manner, is treated with an acid aqueous solution containing zinc cation (Zn and fluorine anion (F) in a zinc content of 0.35 to 14 percent by weight.

In a preferable embodiment of the present invention, the acid aqueous solution containing the zinc cation and the fluorine anion may be prepared by dissolving a zinc compound selected from the class consisting of zinc oxide, zinc hydroxide, zinc nitride, zinc sulfide and zinc salts into an aqueous solution of 5 to 50 percent by weight of hydrofluoric acid in a zinc content in a range from 0.35 to 14 percent by weight.

The zinc salts usable for the above-mentioned acid aqueous solution may be selected from the group consisting of zinc fluoride, zinc chloride, zinc bromide, zinc iodide, zinc chlorate, zinc cyanate, zinc nitrate, zinc thiocyanate, zinc carbonate, zinc phosphate, zinc pyrophosphate, zinc sulfate, zinc dihydrogen phosphate, zinc ammonium chloride, zinc ammoniumsulfate, zinc dithionate, zinc oxalate, zinc acetate and the like. When the above-mentioned zinc compounds are dissolved in the aqueous solution of the hydrofluoric acid, the zinc cation is derived from the zinc compounds. For example, the zinc oxide is dissolved in the hydrofluoric acid so as to produce the zinc cation (Zn**) in accordance with the chemical equations as shown below.

In another preferable embodiment of the present invention, the acid aqueous solution may be prepared by dissolving a water-soluble zinc salt into an aqueous solution of 5 to 20 percent by weight of acid ammonium fluoride in a zinc content of 0.35 to 14 percent by weight.

The above-stated water-soluble zinc salt may be selected from the group consisting of zinc fluoride, zinc chloride, zinc bromide, zinc iodide, zinc chlorate, zinc ammonium chloride, zinc dithionate, zinc nitrate, zinc thiocyanate, zinc sulfate, zinc ammonium sulfate, zinc acetate and the like. This acid aqueous solution can contain the zinc cation derived from the water-soluble zinc salts (for example, ZnSO, Zn S0,) and the fluorine anion derived from the acid ammonium fluoride (NI-L'F-HF 2 NHK 2F H).

When the beryllium article is treated with the acid aqueous solution in accordance with the method of the present invention, the zinc cation (2) contacted with the metallic beryllium surface is reduced into a metallic zinc (Zn) by the reducing action of the metallic beryllium and thus precipitated onto the surface of the beryllium article. Contrarily, the metallic beryllium (Be) contacted with the zinc cation is ionized to beryllium cation (Be**) and thus dissolved into the acid aqueous solution. Through the procedure as stated above, the

surface of the beryllium article is uniformly plated with the metallic zinc.

Especially, the acid aqueous solution of zinc sulfate (ZnSO and acid ammonium fluoride (Nl-L, F-HF) is very preferable for the method of the present invention owing to a high uniformity of the plating.

Referring to the accompanying drawing, the precipitation quanity Q in mg of zinc and the dissolution quantity Q in mg of beryllium are equilibrated after treating the beryllium article with the acid aqueous solution containing 5 percent by weight of zinc sulfate and percent by weight of acid ammonium fluoride for approximately 100 seconds. In other words, after treating for 100 seconds, the precipitation of the metallic zinc and the dissolution of the beryllium cation are stopped. That is, through the treating for 100 seconds, the surface of the beryllium article is completely covered with the metallic zinc layer so that the beryllium surface can not contact the acid aqueous solution. This is very valuable for evenly plating the beryllium article with a uniform thickness of the metallic zinc layer.

The plating procedure according to the present invention is preferably carried out at a temperature of 10 to 50C for 5 to 600 seconds, more preferably at a temperature of to 25C for 5 to 200 seconds. The plating temperature and time may be controlled in consideration of the composition of the plating acid aqueous solution and size and form of the beryllium article.

It is preferable that the beryllium article to be plated is pretreated, before the plating procedure, with an aqueous solution of a mixed acid consisting of 5 to 15 percent by weight of hydrofluoric acid and 5 to 15 percent by weight of phosphoric acid in order to clear the surface of the beryllium article. The pretreatment is valuable for obtaining a high fixedness, that is, a high resistance against peeling between the beryllium surface and the zinc layer. The pretreatment is preferably carried out at a temperature 10 to 30C for 10 to 120 seconds.

Further, the pretreated beryllium article is preferably pretreated, before the plating procedure, with an aqueous solution of 10 to 30 percent by weight of nitric acid. This further pretreatment is effective for eliminating smutson the surface of the beryllium article and may be effected at a temperature of 10 to 30C for 3 to 10 seconds.

The article which results from the method of the present invention is evenly plated with the metallic zinc layer so as to protect the surface of the beryllium article which has a high chemical activity. Also, the plated zinc layer is valuable for further plating the beryllium article with copper, silver, gold, nickel, chromium and the like in a high uniformity and fixedness.

The following examples are inclined for a further understanding of the present invention.

EXAMPLE 1 A beryllium plate having a length of 10 cm, a width of 2 cm and a thickness of 0.05 cm was firstly pretreated with an aqueous solution containing 2 ml/l of hydrofluoric acid of 50 percent by weight concentration and 100 mil] of phosphoric acid of 98 percent by weight concentration at a temperature of 25C for 30 seconds. After rinsing with water, the first pretreated beryllium plate was immersed into an aqueous solution containing 200 ml/l of nitric acid of percent by weight concentration at a temperature of C for 5 seconds. An acid aqueous solution was prepared by dissolving 50 g of zinc oxide into 1,000 m of an aqueous solution containing g of hydrofluoric acid.

The pretreated beryllium plate was immersed into the above acid aqueous solution at a temperature of 25C for seconds, and then rinsed with water.

The result was subjected to the microscopic determination of thickness of the metallic zinc layer. The average deposition of the zinc layer was 10 mg/cm Also, the result was subjected to measurement of resistance for repeated heating and cooling. Through the measurement wherein the result is repeatedly exposed 5 times at a temperature of 40C for 1 hour for 1 cycle and a temperature of 280C for 1 hour for 1 cycle, no alteration was found on the result.

Further, the result was plated with copper with a thickness of 20 pm by the conventional strike and electrolytic copper plating procedure at a favorable condition. The copper layer plated on the zinc layer of the beryllium article had a high resistance against peeling.

EXAMPLE 2 The procedure of Example I was repeated using 300 g of zinc phosphate instead of the zinc oxide. The resultant zinc layer on the beryllium substrate had an average thickness of 0.] am and a high resistance against peeling from the beryllium substrate.

EXAMPLE 3 The procedure of Example 1 was repeated except that the pretreated beryllium plate was immersed into an aqueous solution containing 100 g/l of acid ammonium fluoride and 50 g/l of zinc sulfate instead of the aqueous solution of zinc oxide and hydrofluoric acid.

The resultant zinc layer on the beryllium substrate had an average thickness of 0.1 pm and a high resistance against peeling from the beryllium substrate.

EXAMPLE 4 The procedure of Example 3 was repeated using 83 g of zinc chloride instead of the zinc sulfate. The resultant zinc layer or the beryllium substrate had an average thickness of 0.1 pm and a high peeling resistance.

What we claim is:

l. A method of plating a beryllium article with zinc comprising treating a beryllium article with an acid aqueous solution containing zinc cation (Zn**) and fluorine anion (F) in a zinc content 0.35 to 14 percent by weight and a fluoride content equivalent to 5 to 50 percent by weight of hydrofluoric acid.

2. A method as set forth in claim 1, wherein said acid aqueous solution is prepared by dissolving at least one soluble zinc compound selected from the class consisting of zinc oxide, zinc hydroxide, zinc nitride, zinc sultide and zinc salts into an aqueous solution of 5 to 50 percent by weight of hydrofluoric acid in a zinc content of 0.35 to 14 percent by weight.

3. A method as set forth in claim 2, wherein said soluble zinc compound is selected from the group consisting of zinc oxide, zinc hydroxide, zinc nitride, zinc sulfide, zinc chloride, zinc bromide, zinc iodide, zinc chlorate, zinc cyanate, zinc nitrate, zinc carbonate, zinc thiocyanate, zinc phosphate, zinc pyrophosphate, zinc sulfate, zinc dihydrogen phosphate, zinc ammonium chloride, zinc ammonium sulfate, zinc dithionite, zinc oxalate and zinc acetate.

4. A method as set forth in claim 1, wherein said acid aqueous solution is prepared by dissolving a soluble zinc salt into an aqueous solution of 5 to 20 percent by weight of acid ammonium fluoride in a zinc content of 0.35 to 14 percent by weight.

5. A method as set forth in claim 4, wherein said soluble zinc salt is selected from the group consisting of zinc fluoride, zinc chloride, zinc bromide, zinc iodide, zinc chlorate, zinc ammonium chloride, zinc dithionite, zinc nitrate, zinc thiocyanate, zinc sulfate, zinc ammonium sulfate and zinc acetate.

6. A method as set forth in claim 1, wherein said beryllium article is pretreated with an aqueous solution of a mixed acid consisting of 5 to 15 percent by weight of hydrofluoric acid and 5 to 15 percent by weight of phosphoric acid in order to clear the surface of said beryllium article before said plating.

7. A method as set forth in claim 6, wherein said pretreated beryllium article is further pretreated with an aqueous solution of 10 to 30 percent by weight of nitric acid in order to eliminate smut on said cleared surface of said beryllium article before said plating.

8. A method as set forth in claim 1, wherein said treating is effected at a temperature of 0 to 50C.

9. A method as set forth in claim I, wherein said treating is carried out for 5 to 600 seconds.

10. A method as set forth in claim 6, wherein said pretreating is effected at a temperature of 10 to 30C for 10 to seconds.

1 l. A method as set forth in claim 7, wherein said further pretreating is effected at a temperature of 10 to 30C for 3 to 10 seconds. 

2. A method as set forth in claim 1, wherein said acid aqueous solution is prepared by dissolving at least one soluble zinc compound selected from the class consisting of zinc oxide, zinc hydroxide, zinc nitride, zinc sulfide and zinc salts into an aqueous solution of 5 to 50 percent by weight of hydrofluoric acid in a zinc content of 0.35 to 14 percent by weight.
 3. A method as set forth in claim 2, wherein said soluble zinc compound is selected from the group consisting of zinc oxide, zinc hydroxide, zinc nitride, zinc sulfide, zinc chloride, zinc bromide, zinc iodide, zinc chlorate, zinc cyanate, zinc nitrate, zinc carbonate, zinc thiocyanate, zinc phosphate, zinc pyrophosphate, zinc sulfate, zinc dihydrogen phosphate, zinc ammonium chloride, zinc ammonium sulfate, zinc dithionite, zinc oxalate and zinc acetate.
 4. A method as set forth in claim 1, wherein said acid aqueous solution is prepared by dissolving a soluble zinc salt into an aqueous solution of 5 to 20 percent by weight of acid ammonium fluoride in a zinc content of 0.35 to 14 percent by weight.
 5. A method as set forth in claim 4, wherein said soluble zinc salt is selected from the group consisting of zinc fluoride, zinc chloride, zinc bromide, zinc iodide, zinc chlorate, zinc ammonium chloride, zinc dithionite, zinc nitrate, zinc thiocyanate, zinc sulfate, zinc ammonium sulfate and zinc acetate.
 6. A method as set forth in claim 1, wherein said beryllium article is pretreated with an aqueous solution of a mixed acid consisting of 5 to 15 percent by weight of hydrofluoric acid and 5 to 15 percent by weight of phosphoric acid in order to clear the surface of said beryllium article before said plating.
 7. A method as set forth in claim 6, wherein said pretreated beryllium article is further Pretreated with an aqueous solution of 10 to 30 percent by weight of nitric acid in order to eliminate smut on said cleared surface of said beryllium article before said plating.
 8. A method as set forth in claim 1, wherein said treating is effected at a temperature of 0* to 50*C.
 9. A method as set forth in claim 1, wherein said treating is carried out for 5 to 600 seconds.
 10. A method as set forth in claim 6, wherein said pretreating is effected at a temperature of 10* to 30*C for 10 to 120 seconds.
 11. A method as set forth in claim 7, wherein said further pretreating is effected at a temperature of 10* to 30*C for 3 to 10 seconds. 